In this book, Lederman attempts to explain the significance of the search for the God Particle. In order to do this, one must grasp the history of physics, and the discoveries that have been made thus far. Lederman does this in a humorous way from the bias of an experimental physicist.
Democritus is the first known scientist to have predicted an indivisible, invisible particle. He imagined cutting an object into smaller and smaller pieces with an infinitely sharp knife. Eventually, he said, it would get down to a basic particle that could be cut no smaller. He called this particle “atomos,” Greek for uncuttable. However, he believed that there was a different atom for each material, each with a different shape. John Dalton jumped the gun in the early 1800s when he gave the name “atom” to the basic units of the chemical elements. We now know that those are divisible.
Aristotle is generally credited with holding up the progress of physics for 2,000 years. Galileo finally had the nerve to bring attention to his errors. Aristotle said that heavy objects fall faster than light objects. Also, he said, if you roll a ball, it eventually comes to rest, so rest is natural, whereas motion requires a force to keep it moving. Aristotle’s conjectures were intuitive, and for so many years scientists accepted them without question.
Galileo saw the laws of physics as being represented by mathematics--parabolas and quadratic equations. He saw the simplicity in physics, provided that he could remove all the complicating factors such as air resistance and friction. With no air resistance, two object, no matter what the weight, fall at the same rate. A ball rolling on a horizontal surface would roll forever if there is no friction.
There have been thousands of other physicists that have helped shaped Galileo’s model. With the addition of the particle accelerator and quantum physics, physicists now have what is currently the standard model. So far, the “secret to the universe” is the following model. Matter is divided into two family: quarks and leptons. There are three pairs of quarks: up, down; charm, strange; top, bottom. Each of these quarks comes in three “colors,” so there are 18 total. There are six leptons: electron, electron neutrinos, muon, muon neutrinos, tau, and tau neutrinos. All other particles come out of these. Then there are the force particles, called gauge bosons. The photon is the gauge boson for electromagnetism; W minus, W plus, and Z zero for the weak force; and eight gluons for the strong force. The fourth known force is gravity, but so far the particle (if one exists) has eluded physicists. Then there are the anti-matter particles, making a total of 60 “atoms.” Not quite the one indivisible, invisible particle.
The neutrinos is a strange particle. Here the properties of the electron neutrinos, for example: It has no electric charge, no strong or electromagnetic force, no size or spatial extent (its radius is zero), and it may not have a mass. It has been calculated that to ensure a collision of a neutrinos with matter, the target must be a “block” of lead one light-year thick! For a neutrinos to collide hard in an inch-thick slab of steel would be as likely as finding a certain pebble in the Atlantic ocean--that is, as likely as catching it in a cup of water, randomly sampled. What the neutrinos does have is chirality. Chirality deals with the direction of spin in regard to the direction of motion. Particles can have “right-handed” or “left-handed” spin, clockwise or counterclockwise, respectively. The neutrinos always is left-handed, and the antineutrino always right-handed. Although physicists haven’t yet found a mass for the neutrinos, if it has any, an argument can be made for it having zero mass. Mass breaks down chirality. Once a particle has mass, it travels at speeds less than that of light (theory of relativity). That means that the observer can go faster than the particle. Then, relative to you, the particle has reversed its direction of motion but not its spin, so to the observer, the spin varies.
Before I go further with the particles, I’m going to explain the way they were discovered. Lederman is one of the pioneers of the particle accelerator, a particle microscope. Particle accelerators work by shooting particles around a circular ring, increasing in velocity as they pass a gigantic magnetic. As the particle gains more speed, one of two things must happen: the radius of its trajectory must increase, or the magnetic field must get stronger. The latter of the two is the obvious method in use in the accelerators. The magnetic field must increase in synchronization with the acceleration of the particle.
The Tevatron, a trillion-electron-volt machine, is four miles in diameter. Particles make 50,000 orbits around this track every second. In 10 seconds the particles have traveled 2 million miles. The magnets that keep the particles focused allow them to deviate from their appointed rounds by less than one eighth of an inch over the entire trip. It’s like aiming a rifle at a mosquito sitting on the moon but hitting it in the wrong eye. There are two types of accelerators: one that uses protons, and one that uses electrons. Electron accelerators use the circular track mentioned above. Proton accelerators are straight. It is actually straight. Surveyors standing on earth can guarantee that a road is straight, but it actually follows the slight curve of the earth. If the earth were a perfect sphere, linear accelerators would be a tangent to the earth’s surface.
Accelerators make anti-particles (positrons, for example) and crash them into their matter counterpart, in this case the electron. Unlike matter collisions, when a positron collides with an electron, both particles disappear. Total annihilation. In their place, energy is created, in the form of a photon. Then the photon creates two other particles: sometimes another electron and positron. The photon may also dissolve into a muon and antimuon, or even a proton and antiproton. When a nuclear bomb explodes, only a fraction of one percent of the atomic mass is actually converted into energy. In the burning of coal or oil, only one billionth of the mass is converted to energy. In fission reactors this number is 0.1 percent, and fusion energy is about 0.5 percent. Antimatter would provide an unlimited supply of energy, but currently, using antimatter for fuel is a long way off. In has been determined that one milligram of antiprotons would be an ideal rocket fuel (containing energy equal to about two tons of oil). As of now, Fermilab is the world leader in antiproton production with about 100,000,000,000 per hour. At this rate, it would take a few million years of twenty-four-hour operation to produce one milligram.
One way to look at particle accelerators is as a time machine. Astrophysicists have determined that the world was created about 15 billion years ago after a “big bang.” In the earliest instants after the Big Bang, the universe was a hot, dense collection of particles (or one particle) with energies vastly higher than anything we can imagine. So far, we know the universe from time 10-33 seconds up to the present, 1017 seconds. As the universe expanded, it cooled, and somewhere around 10-12 seconds, the universe was reduced to one trillion volts. This is the same energy as the Tevatron can replicate. So, during head-on collisions of protons in the accelerator, it replicates the behavior of the entire universe at age a millionth of a millionth of a second. The higher the energy of the accelerator, the farther back in time it goes.
One other important concept: Einstein’s famous E=mc2. As particles gain speed in the accelerator, they also gain energy. According the the formula, as energy increases, the mass also increases (the speed of light squared is a constant). Millions of dollars are spent to build bigger, more powerful accelerators, sometimes just to increase accelerating speed from 99.99 percent of the speed of light to 99.999. This may seem like a waste of money, but it is not the speed that physicists are worried about. It is the energy. In a small jump nine thousands of a percent, the energy increases enormously. As the energy increases, new particles are discovered as they shoot out of collisions. The energy at which new particles are formed is the given mass of a particle. However, the mass is only a probability. The actual mass cannot be determined.
Quarks were first discovered in 1964. Quarks can never be alone--they arrange themselves in different combinations to create other particles. For example, two “up” quarks and one “down” quark make up a proton. One up and two downs make up a neutron. Quarks make up all the hadrons (Greek for “heavy”). Hadrons are divided into two groups: baryons and mesons. Baryons are made up of three quarks, mesons two. Included in the groups are protons, neutrons, lambdas, sigmas, xis, pions, kaons, and others. A property of quark pairs is that the farther away they are pulled from eachother, the more energy they require to separate them. When enough energy is used to separate them, an quark-antiquark pair is created, so there are then four quarks. It is like trying to take home one end of a single string. You snip it and you have two strings.
A brief explanation of the forces. The strong force is the force that binds a pair of quarks together, and keeps the nucleus of an atom together. It is theorized that a particle, called the gluon, jumps rapidly back and forth, somehow keeping two particles together. The weak force is the force that causes particles to decay. The electromagnetic force is way to describe how force is transmitted between two matter particles. And the fourth, gravity, has yet to have a particle discovered for it. Scott Adams has a hypothesis in one of his books. It doesn’t explain gravity completely by any means, but it is a way to visualize gravity (and without any little particles). Imagine a universe where all matter is expanding (or the space between each particle is expanding. This is not so far-fetched, because we know that the universe as a whole is expanding. You, standing on earth, would be expanding at a rate proportional to the earth and everything else, so you wouldn’t notice the expansion, in the same way that we don’t notice traveling at a velocity of around 1000 miles per hours as the earth rotates. If you tried to jump away from earth, it would quickly catch up to you. This effect would cause us to be pulled toward earth, hence gravity. Because the universe is expanding, the planets would never hit eachother. However, here are my problems with this hypothesis. One, it doesn’t explain the revolution of the earth around the sun, and the sun around the center of the galaxy. Also, if the universe’s expansion rate is slowing down, the the effect of “gravity” is getting less and less. Uh, oh. Anyway, back to the book.
A relatively new idea is that all of space contains a field, named the Higgs field. It would permeate everything and be the same everywhere. Particles, influenced by this field would acquire mass (in fact, all of a particle’s mass may come from this field). Certain particles would be influenced by this field more than others, hence a variance in particle’s masses. The Higgs boson, therefore, would be a zero-spin boson, meaning no directionality, that would give mass to things everywhere. One problem with Higgs: at low temperatures, it doesn’t seem to work. It is only when energy gets above 1 TeV. An analogy of how this works is a balloon filled with steam. There is perfect symmetry, the same throughout. If you let it cool, you will get a liquid at the bottom, with possible ice floating in it. The symmetry is broken just by the simple act of cooling. There are theories that give estimates as to the mass of the Higgs, and it is not far into the future when there will be an accelerator strong enough to find it.
However, I believe that we are nowhere near finding the true “atom,” as we are not remotely close to replicating energies of the Big Bang (energies estimated at 1019 GeV, or a trillion times the energy of the biggest collider). At the time of the Big Bang, I think that there must have been a universe in which there was only one particle, obeying one law. This law still governs the universe as we know it, but low energies have made it impossible to comprehend in any experiment or theory the Law of the universe.
